04-07-2025
‘Argentina's top aquatic predator' released in wild for first time. ‘Huge win'
In a wetland of northeastern Argentina, a family of the country's 'top aquatic predator' ventured outside their enclosure for the first time. They didn't run or even wander very far, but that wasn't the point.
The family's release into the wild marked a conservation milestone for a species considered locally extinct for about 40 years.
Conservationists began this ambitious project eight years ago with one goal: bring giant river otters back to Argentina, Tompkins Conservation, one of the organizations involved, said in a June 27 Facebook post.
Giant river otters, or Pteronura brasiliensis, are the world's largest otters, reaching almost 6 feet long and weighing up to 72 pounds, Rewilding Argentina said in a news release. The species is considered endangered globally and went locally extinct in Argentina in the late 1980s due to hunting and habitat loss.
'With no wild or captive individuals left in Argentina, the (reintroduction) process had to start from scratch,' Tompkins Conservation said.
First, conservationists prepared a spot for the otters in the Iberá Wetlands, a vast protected area, by building semi-aquatic enclosures to keep the animals contained while allowing them to adjust to the natural environment. Next, the team found zoos in the United States and Europe willing to donate otters to the project and transferred the animals to the new enclosures.
'Since giant river otters live and hunt in large family groups, their release into the protected Iberá wetlands has been contingent on their forming a family,' the United Nations Environment Programme said in a 2024 news release about the project.
Conservationists oversaw the giant river otters as they learned to fish, formed mating pairs and had pups. Simultaneously, the team prepared special otter harnesses fitted with tracking devices to monitor the animals post-release.
This yearslong process led one otter family — Coco, Nima and their two pups — to be ready for release, Sebastián Di Martino, the conservation director at Rewilding Argentina, told McClatchy News via email.
On July 1, conservationists opened up the otter family's enclosure and set them free. Photos show the giant river otters standing on a dock outside their enclosure, swimming in the open water and approaching a research truck.
The day marked several firsts: the project's first otter release, the first time otters had lived in the wild in Argentina in decades and 'the first worldwide comeback of this species in a habitat where it had been rendered extinct,' Tompkins Conservation said.
Since the release, the otters are 'staying relatively close to their enclosure,' Di Martino said. 'The territory of this group is defined in and around the enclosure, which is why it's logical for them to stay in that area and gradually begin to explore a bit more.'
'They go out, swim around a bit, and then return to the enclosure,' Di Martino said. 'There's a lot of exploratory movements. They vocalize a lot to stay in contact and together. And they've even been swimming a lot. Of course, sometimes they come out onto land, onto the shore a bit, and they've also already caught some fish.'
Conservationists are preparing more otter families for reintroduction to the Iberá Wetlands but have no estimated timeline for their release.
'Since this is the first giant river otter reintroduction project in the world, each step we take comes with a lot to learn,' Di Martino said.
Still, 'the giant river otter's return marks a huge win for the communities of Northeast Argentina, all the park visitors and the natural world,' Kris Tompkins, the president of Tompkins Conservation, said in a Facebook post.
Google Translate was used to translate the news release from Rewilding Argentina.
